Artificial bristle and method of making same



July 9, 1940.

1 N V E NTO R S Ham/y ,4. @171!!! svlfillzam [wigs ATTORNEY PatentedJuly 9, 1940 UNITED STATES ARTIFICIAL mus'rm AND rnrrnon or MAKING SAMEHarvey A. Neville and William 0. Forbes, Bethlehem, Pa., assignors toDevoe & Raynolds 00., Inc., a corporation of New York ApplicationOctober 7,

9 Claims.

In our co-pending application, Ser. No. 147,312, filed June 9, 1937, wedescribe a process of making artificial bristles by coating several(preferably three) strands of a textile fiber with a resinous materialand then aggregating such strands in parallel arrangement into a unitarybristle structure which is cut to length after the resin is dried andbaked. In that application we describe a process of tapering thebristles by w varying the amount of resin applied to the body.

According to the present invention, we make tapered bristles byproviding a yarn or strand element which itself is tapered over a lengthapproximately equal to the desired length of the bristles. As in theearlier application, these strands are coated with a resinous body andthen a plurality (preferably three) of such strands are brought togetherso that the resin serves to bond them into a unitary structure, afterwhich they are dried, baked and cut into lengths. Of course, care shouldbe taken so that the enlarged portions of the tapered strands arebrought together so that the final bristle has a taperwhich is afunction of the sum of the tapers of the separate strands.

We have also found it desirable in the manufacture of such bristles toapply a thin protective coating to the bristle after the resin is driedand prior to the final baking operation. By the use of such protectivecoating, the. bristles can be dried in large bundles or aggregateswithout danger of the resin of one-bristle adhering to the resin of thenext. For such purpose, various Water-so1uble, non-thermoplastic bodiesmay be 35 employed, such for example, as gelatin or-glue or it may bepossible to use a flaxseed mucilage for this purpose. Such coatingshould be dried before the bristles are given their final baking.

For the purpose of illustration, a strand of fiber for use in connectionwith this invention may, for example, be a cellulose acetate yarn whichmay have an average diameter equal to that of a 150 denier yarn andranging from a maximum diameter approximately that of a 225 denier yarndown to a minimum diameter equal to that of a '75 denier yarn. Thedistance from one point of maximum diameter to the next point of maximumdiameter may for example be inches so that the bristles when out apartwill each have a length of approximately 5 inches. As is usual with suchyarns, the yarn which we employ is ordinarily made up of a number ofacetate filaments.

An example of the resin varnish which can 55 be used for coating thismaterial is one prepared 1937, Serial No. 167,702 (01. 154-2) from 100pounds of oil-soluble phenolic resin and having a China wood contentwhich may range from approximately 12 gallons up to approximately 25gallons and this range may be further modified if desired. The oil andresin are cooked together to produce a very quick-drying varnish andsome pigment such as carbon black may be included. As is usual with suchproducts, the varnish is thinned with any usual type of thinner, forexample to the point where the resulting product contains between 50%and 85% of solids. The thinner solutions can ordinarily be used forbatch dipping processes, whereas, the thicker solutions are needed forcontinuous drawing.

In the drawing, we show a strand of artificial bristle. The drawing isvery much enlarged and possesses, for clarity, a precision of line whichdoes not obtain in the actual bristle.

Fig. 1 is a front view showing a single strand of uncoated taperedtextile fiber; Fig. 2 is a front view partly in section showing a singlestrand of the tapered textile fiber with a preliminary coating; Fig. 3shows a perspective view showing a group of three coated tapered strandsand an end View showing the trefoil cross section of the bristles, andFigs. 4 and 5 are sections taken along the lines 4-4 and 5-5 of Fig. 3.

Ordinarily, the distance along the strand between the points of maximumdiameter is approximately 10 inches. Bristles cut from such strands,therefore, generally run to about 5 inches in length.

The basic tapered strand of textile fiber is indicated in the drawing bythe numeral Hi. This tapered strand is coated with a preliminaryresinous coating l2. Groups of strands coated as shown in Fig. 2 arethen brought together, preferably in the trefoil cross sectional patternshown in Fig. 3 and are dipped in another coating M of a resinouscomposition. Care must be taken to have the tapered strands groupedtogether so that the taper of the final bristle is a function 'of thetapers of the several strands.

As stated, we prefer to use three strands of the yarn so that theresulting bristle will have a trefoil cross-section as we have foundthat this shape of bristle has particular advantages. Further details inregard to the various types of resin that may be employed and thedetailed steps of operation are set forth in: our earlier applicationabove referred to.

What we claim is:

1. An artificial bristle comprising a plurality of strands of taperedtextile fiber running approximately parallel to one another and bondedtogether by a coating oi! resinous substance to form a bristle-likeaggregate having a taper which is a composite of the tapers of theseveral strands.

2. An artificial bristle as specified in claim 1 wherein the textilefiber is in the form of substantially continuous strands tapering towardone end.

3. An artificial bristle as specified in claim 1 wherein the textilefiber consists essentially of a tapered strand of cellulose acetate.

4. An artificial bristle of trefoil cross section comprising threetapered strands of cellulose acetate, said strands being insubstantially parallel arrangement with their large ends together andbeing bonded together by means of a resinous substance to form a unitarystructure having a taper which is a function of the sum of the tapers ofthe three tapered strands.

5. A process for forming artificial bristles which comprises coatingtapered strands of a textile fiber with a resinous solution, bringingsuch strands together so that the resinous substance binds them into anaggregate having a taper which is a composite of the tapers of theseveral strands, drying the strands, coating the aggregated strands witha water-soluble, nonthermoplastic substance, drying and baking thecoated aggregate and cutting the aggregate at approximately the placesof maximum and minimum diameter to form bristles of desired lengths.

6. A process as specified in claim 5 wherein the water-soluble,non-thermoplastic liquid comprises gelatin.

7. A process as specified in claim 5 wherein the water-soluble,non-thermoplastic liquid comprises glue.

8. A process as specified in claim 5 wherein the water-soluble,non-thermoplastic liquid comprises fiaxseed mucilage.

9. A process for forming artificial bristles which comprises coatingtapering strands of a textile fiber with a'resinous solution, bringingsuch strands together so that the resinous substance binds them into anaggregate having a taper which is a composite of the tapers of theseveral strands, drying and baking the coated aggregate and cutting thestrands at approximately their widest and narrowest portions.

HARVEY A. NEVILLE. WILLIAM C. FORBES.

